Event-Driven Architecture

The basics of adding realtime data push to your serverless backend

Serverless

Serverless is one of the developer world’s most popular misnomers. Contrary to its name, serverless computing does in fact use servers, but the benefit is that you can worry less about maintenance, scale, and configuration. This is because serverless is a cloud computing execution model where a cloud provider dynamically manages the allocation of machine and computational resources. You are basically deploying code to an environment without visible processes, operating systems, servers, or virtual machines. From a pricing perspective, you are typically charged for the actual amount of resources consumed and not by pre-purchased capacity.

Pros

Reduced architectural complexity

Simplified packaging and deployment

Reduced cost to scale

Eliminates the need for system admins

Works well with microservice architectures

Reduced operational costs

Typically decreased time to market with faster releases

Cons

Performance issues — typically higher latency due to how commute resources are allocated

Vendor lock-in (hard to move to a new provider)

Not efficient for long-running applications

Multi-tenancy issues where service providers may run software for several different customers on the same server

Difficult to test functions locally

Different FaaS implementations provide different methods for logging in functions

AWS Lambda

Amazon’s take on serverless comes in the form of AWS Lambda. AWS Lambda lets you run code without provisioning or managing servers — while you only pay for your actual usage. With Lambda, you can run code for virtually any type of application or backend service — Lambda automatically runs and scales your application code. Moreover, you can set up your code to automatically trigger from other AWS services or call it directly from any web or mobile app.

Websockets

A WebSocket provides a long-lived connection for exchanging messages between client and server. Messages may flow in either direction for full-duplex communication. A client creates a WebSocket connection to a server, using a WebSocket client library. WebSocket libraries are generally available in every language, and of course browsers support it natively using the WebSocket JavaScript object. The connection negotiation uses an HTTP-like exchange, and a successful negotiation is indicated with status code 101. After the negotiation response is sent, the connection remains open to be used for exchanging message frames in either binary or unicode string format. Peers may also exchange close frames to perform a clean close.

Building AWS IoT Websockets

Function-as-a-service backends, such as AWS Lambda, are not designed to handle long-lived connections on their own. This is because the function invocations are meant to be short-lived. Lambda is designed to integrate with services such as AWS IoT to handle these types of connections. AWS IoT Core supports MQTT (either natively or over WebSockets), a lightweight communication protocol specifically designed to tolerate intermittent connections.

However, this approach alone will not give you access to the raw protocol elements — and will not allow you to build a pure Lambda-powered API (if that is your intended use case). If you want this access, then you need to take a different approach.

Building Lambda-Powered WebSockets with Fanout

You can also build custom Lambda-powered WebSockets by integrating a service like Fanout — a cross between a message broker and a reverse proxy that enables realtime data push for apps and APIs. With these services together, we can build a Lambda-powered API that supports plain WebSockets.

This approach uses GRIP, the Generic Realtime Intermediary Protocol — making it possible for a web service to delegate realtime push behavior to a proxy component.

This FaaS GRIP library makes it easy to delegate long-lived connection management to Fanout, so that backend functions only need to be invoked when there is connection activity. The other benefit is that backend functions do not have to run for the duration of each connection.

The following step-by-step breakdown is meant as a quick configuration reference. You can checkout the Github libraries for Node and Pythonintegrations.

1. Initial Configuration

You will first configure your Fanout Cloud domain/environment and set up an API and resource in AWS API Gateway to point to your Lambda function, using a Lambda Proxy Integration.

2. Using Websockets

Whenever an HTTP request or WebSocket connection is made to your Fanout Cloud domain, your Lambda function will be able to control it. To do this, Fanout converts incoming WebSocket connection activity into a series of HTTP requests to your backend.

Overall, if you‘re not looking for full control over your raw protocol elements, then you may find it easier to try a Lambda/AWS IoT configuration. If you need more WebSocket visibility and control, then the Lambda+Fanout integration is probably your best bet.

Edge computing is hot right now. The growing maturity of IoT networks ranging from industrial to VR applications means that there’s an enormous amount of discussion around moving from the cloud to the edge (from us as well). But edge computing is only the first step.

We first want to makes sure we define the terms we’ll use.

The edge refers to the devices, sensors, or other sources of data at the edge of the network.

The cloud is the datacenter at the “center” of the network.

The fog is a management layer in-between the two (we know this is vague, read on)

More data, more problems

As more and more devices become connected to networks, we’re going to see an enormous uptick in the amount of data generated. Andy Daecher and Robert Schmid of Deloitte believe that “globally, the data created by IoT devices in 2019 will be 269 times greater than the data being transmitted to data centers from end-user devices and 49 times higher than total data center traffic.” Calling this big data is an understatement.

These volumes of data mean big problems:

Moving this amount of data means latency issues for networks

Privacy and security concerns increase as more data is moved

Devices sending more data require more hardware and power to run

Prioritization is the answer, but it’s not solved at the edge

The answer to increasing data volume is the fog: the prioritization and management layer on the continuum between the edge and the cloud. The fog needs to answer the crucial decision: what to analyze at the end, and what to push back to the cloud?

It’s unreasonable to expect an IoT sensor at the edge (like a drone, that requires sub-millisecond reaction times), to process all the data it collects in realtime or push that data all the way to the cloud for processing. The fog reduces latency and takes the processing load off the drone, acting as a management layer and allowing for efficient distribution of resources across the network.

So, what does architecture incorporating the cloud, the edge, and the fog look like?

Justin Baker of RealtimeAPIHub has an excellent guide, including this graphic from Ergomonitor:

Intelligently separating data analysis tasks across the network continuum will be crucial as we move forward into the next era of IoT.

Learn the basics of edge computing and how it is transforming the realtime landscape

The Edge

The ‘edge’ refers to computing infrastructure that exists close to the origin sources of data. It is distributed IT architecture and infrastructure where data is processed at the periphery of the network, as close to the originating source as possible.

Edge computing is a method of optimizing cloudcomputing systems by performing data processing at theedge of the network, near the source of the data.

Living on the Edge

Examples of edge computing can be found throughout our everyday lives — we just may not notice them.

Industrial Internet of Things (IIoT)

Wind turbines

Magnetic resonance (MR) scanner

Undersea blowout preventers

Industrial controllers such as SCADA systems

Automated industrial machines

Smart power grid technology

Smart streetlights

Internet of Things (IoT)

Motor vehicles (Cars and trucks)

Mobile devices

Traffic lights

Thermostats

Home appliances

TechTarget

Edge Computing Benefits

Edge computing allows for the clear scoping of computing resources for optimal processing.

Time-sensitive data can be processed at the point of origin by a localized processor (a device that has its own computing ability).

Intermediary servers can be used to process data in close geographical proximity to the source (this assumes that intermediate latency is okay, though realtime decisions should be made as close to the origin as possible).

Cloud servers can be used to process less time sensitive data or to store data for the longterm. With IoT, you’ll see this manifest in analytics dashboards.

Edge application services significantly decrease the volumes of data that must be moved, the consequent traffic, and the distance the data must travel, thereby reducing transmission costs, shrinking latency, and improving quality of service(QoS) (source).

Edge computing removes a major bottleneck and potential point of failure by de-emphasizing the dependency on the core computing environment.

Security improves as encrypted data is checked as it passes through protected firewalls and other security points, where viruses, compromised data, and active hackers can be caught early on (source).

Why the Edge

Transmitting massive amounts of data is expensive and taxing on network resources. Edge computing allows you to process data near the source and only send relevant data over the network to an intermediate data processor.

For example, a smart refrigerator does not need to continually send internal temperature data back to a cloud analytics dashboard. Rather, it can be configured to only send data when the temperature has changed beyond a particular point; or, it could be polled to send data only when the dashboard is loaded. Similarly, an IoT security camera could only need to send data back to your device when it detects motion or when you explicitly toggle a live data feed.

Devise Relationship Management (DRM)

To manage edge devices, device relationship management (DRM) refers to the monitoring and maintenance of complex, intelligent, and interconnected equipment over the internet. DRM is specifically designed to interface with the microprocessors and local software in IoT devices.

Device relationship management (DRM) is enterprise software that enables the monitoring, managing, and servicing of intelligent devices over the Internet.

The Fog

Between the edge and cloud is the fog layer, which helps bridge the connections between edge devices and cloud data centers. According to Matt Newton of Opto 22:

Fog computing pushes intelligence down to the local area network level of network architecture, processing data in a fog node or IoT gateway.

Edge computing pushes the intelligence, processing power and communication capabilities of an edge gateway or appliance directly into devices like programmable automation controllers (PACs).

Energomonitor

Edge and Realtime

Sensors and remotely deployed devices demand realtime processing. A centralized cloud system is often too slow for this, especially when decisions need to be made in microseconds. This is especially true for IoT devices in regions or locations with poor connectivity.

According to Mark O’Neill and Paolo Malinverno of Gartner, 50% of managed APIs will support event-driven IT by 2020 (2017 Report). These event-driven APIs will not necessarily replace RESTful request-response architectures, but will become necessary supplements to expand an organization’s functional offerings and overall performance.

In another 2017 IoT report, Gartner projects “8.4 billion connected devices, up 31% from 2016, and will reach 20.4 billion by 2020. Total spending on endpoint infrastructure and services will reach almost $2 trillion in 2017.”

So, what’s driving this evolution? “Realtime” is becoming an omnipresent force in the modern tech stack. As consumers demand faster experiences and more instantaneous data transactions, companies are increasingly investing in product infrastructure that accelerates these transactions. Though we’ve seen APIs become an economic and technological imperative, they are typically based on request-response style interactions, which limits their scope and effectiveness in the realtime arena.

Request-Response vs Event-Driven APIs

At its core, request–response is a message exchange pattern in which a requestor sends a request message to a replier system. The replier system receives and processes the request, and if all goes well, it returns a message in response. While this exchange format works well for more structured requests, it limits integrations to those where the expectant system has a clear idea what it wants from the other. These request-response style APIs, therefore, must follow the interaction script from the calling service.

In an event-driven architecture, applications integrate multiple services and products as equals based on event-driven interactions. These interactions are driven by event emitters, event consumers, and event channels, whereby the events, themselves, are typically significant ‘changes in state’ that are produced, published, propagated, detected, or consumed. This architectural pattern supports loose coupling amongst software components and services. The advantage is that an event emitter does not need to know the state of the consumer, who the consumer is, or how the event will be processed (if at all). It is a mechanism of pushing data through a persistent stream.

The $195 Billion IoT Market

The proliferation and ‘smartening’ of IoT-driven devices is projected to reach a market cap exceeding $195 billion in 2023, according to analysts at ReportsnReports. From a market of $16 billion in 2016, this growth is mainly fueled by the increasingly ubiquitous manufacturing of smarter in-home, mobile, and transportation devices — and the need to capture that data and enhance communication infrastructure.

The smarter devices become, the more data they need to make complex, realtime decisions. Sensors and external data gathering implements are becoming an essential catalyst for IoT industry growth. The accuracy of sensors and actuators that measure geospatial proximity, acceleration, temperature, and motion will separate the industry leaders from the laggards.

Data & Business Intelligence

The goal of a truly interconnected tech ecosystem will also mirror equal growth in data and business intelligence. The more things are interconnected, the more companies will need to gather data, push remote updates, and control devices in the field. Hence, remote communication needs to be reliable, data needs to be accurate, and the ability to extract meaningful information from big data becomes paramount.

In a 2015 report by Seagate, 25% of all data will need to be processed and generated in realtime by 2025 out of a total of 160 Zettabytes.

Realtime is all about pushing data. In a data push model, data is pushed to a user’s device rather than pulled (requested) by the user. For example, modern push email allows users to receive email messages without having to check manually. Similarly, we can examine data push in a more continuous sense, whereby data is continuously broadcasted. Anyone who has access to a particular channel or frequency can receive that data and decide what to do with it.

HTTP Streaming

HTTP streaming provides a long-lived connection for instant and continuous data push. You get the familiarity of HTTP with the performance of WebSockets. The client sends a request to the server and the server holds the response open for an indefinite length. This connection will stay open until a client closes it or a server side-side event occurs. If there is no new data to push, the application will send a series of keep-alive ticks so the connection doesn’t close.

Websockets

WebSockets provide a long-lived connection for exchanging messages between client and server. Messages may flow in either direction for full-duplex communication. This bi-directional connection is established through a WebSocket handshake. Just like in HTTP Streaming and HTTP Long-Polling, the client sends a regular HTTP request to the server first. If the server agrees to the connection, the HTTP connection is replaced with a WebSocket connection.

Webhooks

Webhooks are a simple way of sending data between servers. No long-lived connections are needed. The sender makes an HTTP request to the receiver when there is data to push. A WebHook registers or “hooks” to a callback URL and will notify you anytime an event has occurred. You register this URL in advance and when an event happens, the server sends a HTTP POST request with an Event Object to the callback URL. This event object contains the new data that will be pushed to the callback URL. You might use a WebHook if you want to receive notifications about certain topics. It could also be used to notify you whenever a user changes or updates their profile.

HTTP Long-Polling

HTTP long-polling provides a long-lived connection for instant data push. It is the easiest mechanism to consume and also the easiest to make reliable. This technique provides a long-lived connection for instant data push. The server holds the request open until new data or a timeout occurs. Most send a timeout after 30 to 120 seconds, it depends on how the API was setup. After the client receives a response (whether that be from new data or a timeout), the client will send another request and this is repeated continuously.

And, of course, there is the infrastructure behind it all.

Realtime API Infrastructure – Realtime API infrastructure specifically allows developers to build realtime data push into their existing APIs. Typically, you would not need to modify your existing API contracts, as the streaming server would serve as a proxy. The proxy design allows these services to fit nicely within an API stack. This means it can inherit other facilities from your REST API, such as authentication, logging, throttling, etc. It can be combined with an API management system. In the case of WebSocket messages being proxied out as HTTP requests, the messages may be handled statelessly by the backend. Messages from a single connection can even be load balanced across a set of backend instances.

Main Take-Aways

IoT, big data, and consumer expectations are fueling the proliferation of event-driven / realtime APIs. One of the greatest challenges facing engineers over the next few years will be constructing scalable, fault-tolerant event-driven architectures at scale. This is why we are seeing companies spend more than $2 trillion in 2017 to support event-driven endpoints and infrastructure.

While RESTful architectures will remain a necessity, it is important for organizations to understand and plan for event-driven systems — which add a new dimension of realtime API infrastructure complexity.

The internet is a system of communication, and as such, the relationship between client and server, as well as server to server, is one of the most oft-discussed and hotly contested concepts. event-driven architecture is a methodology of defining these relationships, and creating systems within a specific set of relationships that allow for extensive functionality.

In this piece, we’re going to discuss 5 common event-driven methods — WebSockets, WebHooks, REST Hooks, Pub-Sub, and Server Sent Events. We’ll define what they fundamentally are and do, and how API providers go about using them. Additionally, we’ll provide some pros and cons on each to make choosing a solution for your platform easy and intuitive.

In his article, Martin Fowler discusses the meaning of ‘event-driven’ and all its nuances. He tries to make sense of the various patterns that make up the event-driven landscape.

Towards the end of last year I attended a workshop with my colleagues in ThoughtWorks to discuss the nature of “event-driven” applications. Over the last few years we’ve been building lots of systems that make a lot of use of events, and they’ve been often praised, and often damned. Our North American office organized a summit, and ThoughtWorks senior developers from all over the world showed up to share ideas.

The biggest outcome of the summit was recognizing that when people talk about “events”, they actually mean some quite different things. So we spent a lot of time trying to tease out what some useful patterns might be. This note is a brief summary of the main ones we identified.

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